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A Wireless Temperature Sensor for the Nixie Bargraph Thermometer

A multipurpose solution with a design trick

A Wireless Temperature Sensor for the Nixie Bargraph Thermometer
A Wireless Temperature Sensor for the Nixie Bargraph Thermometer
Having digested Elektor’s Nixie Bargraph Thermometer article [1] one reader based in the American Midwest kindly advised that temperatures in his area easily exceed 85 ˚F (29.5 ˚C) for more than six months. Under these circumstances the original 50–85 ˚F (10–30 ˚C) scale of our thermometer is inconvenient if not useless. In response and in good engineering spirit we expanded the scale to cover 15–105 ˚F (–10 to +40 ˚C) and while at the design desk, we thought we’d turn that thermometer into a wireless device as well. Here goes.
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Materials

Component list

Component List

200136-012-94

200136-014-94

 

Transmitter

 

Resistors

R1 = 0Ω, 1206 *

R2 = 100Ω, 1206

R3 = 4kΩ7, 1206

R4 = 10kΩ, 1206

R5 = 100kΩ, 1206

 

Capacitors

C1,C2 = 22pF, C0G/NP0, 1206

C3-C7 = 100nF, X7R, 1206

C8= 22µF, X5R, 10V, 1206, Kemet C1206C226M8PACTU

 

Semiconductors

IC1 = ATMEGA328P-AU, programmed

IC2 = DS2438Z+

MOD1 = TXM-433-LR, Linx Technologies (USA/Canada alternative: TXM-315-LR)

 

Miscellaneous

ANT1 = 433MHz helical PCB antenna, Pulse Electronics type W3127 (USA/Canada alternative: W3126)

B1 = CR2450 battery holder, Renata type SMTU 2450N-1-LF, w. CR2450 coin cell lithium battery

K1 = 10-pin (2x5) boxheader, 2.54mm pitch (optional)

K2 = 3-pin pinheader, vertical, 2.54mm pitch (optional)

S1 = tactile switch, SMT, TE Connectivity type FSM6JSMA

X1 = 8MHz quartz crystal, Abracon type ABMM2-8.000MHZ-E2-T or Würth Elektronik # 830055663

 

* see text

 

Note: a kit of parts for the transmitter is available from the Elektor Store.

Component List

200136-009-94

200136-010-94

 

 

Receiver

 

Resistors

R1 = 10Ω, 1206

R2 = 100Ω, 1206

R3 = 220Ω, 1206

R4,R5 = 4kΩ7, 1206

R6,R7 = 10kΩ, 1206

 

Capacitors

C1,C2 = 22pF, C0G/NP0, 1206

C3-C6 = 100nF, X7R, 1206

C7,C8 = 1µF, X7R, 1206

C9 = 22µF, X5R, 10V, 1206, Kemet C1206C226M8PACTU

 

Semiconductors

LED1 = green, 1206, Broadcom Limited type HSMG-C150

IC1 = ATMEGA328P-AU, programmed

IC2 = LD39015M33R

MOD1 = RXM-433-LR, Linx Technologies (USA/Canada alternative: RXM-315-LR)

T1 = BSN20

 

Miscellaneous

ANT1 = 433MHz helical PCB antenna, Pulse Electronics type W3127 (USA/Canada alternative: W3126)

K1 = 10-pin (2x5) boxheader, 2.54mm pitch (optional)

K1 = 3-pin pinheader, vertical, 2.54mm pitch (optional)

K3 = 3-pin pinheader, angled, 2.54mm w. female terminal housing # 61900311621 and 3 pcs pre-crimped cable # 619100126015 (Würth Elektronik)

L1,L2 =ferrite bead, Fair-rite type 1206 2512067007Y3

S1 = tactile switch, SMT, TE Connectivity type FSM6JSMA

X1 = 8MHz quartz crystal, Abracon type ABMM2-8.000MHZ-E2-T or Würth Elektronik # 830055663

 

Note: a kit of parts for the receiver is available from the Elektor Store.

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